Make the base, process the biscuits to make rough crumbs and then add the butter and cocoa. Process again until it makes damp, clumping crumbs and then tips them into a 23cm springform tin. Press the biscuit crumbs into the bottom of the tin to make an even base and put into the freezer while you make the filing.

Preheat the oven to 180’C. Put a kettle on to boil. Melt the chocolate either in a microwave or double boiler, and set aside to cool slightly.

Beat the cream cheese to soften it and then add the sugar and cornflour, beating again to combine. Beat in the whole eggs and then the yolks, and the sour cream. Finally add the cocoa dissolved in hot water and the melted chocolate, and mix to a smooth batter.

Take the springform tin out of the the freezer and line the outside of the tin with a good layer of clingfilm, and then another layer of strong foil over that. This will protect it from the water bath. Sit the springform tin in a roasting pan and pour in the cheesecake filing.

Fill the roasting pan with just-boiled water to come about halfway up the cake tin, and bake in the oven for 45 minutes to an hour. The top of the cheesecake should be set, but the underneath should still have a wobble to it.

Peel away the foil and clingfilm wrapping and sit the cheesecake in its tin on a rack to cool. Put in the fridge once it’s no longer hot, and leave to set, covered with clingfilm, overnight.

Let it lose its chill before unspringing the cheesecake to serve.

To make the chocolate glaze, very gently melt the chopped chocolate and cream. When the chocolate has nearly melted, take off the heat and whisk it to a smooth sauce. Add the golden syrup and mix well. Add the warm water then mix till you got a smooth chocolate glaze.

Pour it evenly on the center of the chocolate cheesecake. Chill in the fridge for few minutes until the glaze slightly set.